The present invention relates to rigid hoses, and namely to hoses that remain in a generally round shape which can be used for either pressure or suction service, as opposed to hoses that lay flat for storage and become round when pressure is applied. The present invention relates especially to hoses having a spiral bead or helical rib protruding from their exterior and more particularly concerns an apparatus for securing couplings or fittings to the ends of a spiral bead hose.
Spiral bead hoses provide a fluid connection from a source, such as a pond, to a destination such as a pump. For example, spiral bead hoses may be used for drafting water at the site of a fire. Spiral bead hoses are frequently used in applications involving low pressure or vacuum use, for which the flat, expandable type of hose is inadequate. In these applications, the hose must be rigid to maintain a flow path and yet flexible enough to turn and bend to easily conform to the route from the source to the destination.
Spiral bead hoses are made by simultaneously extruding two or more materials in a helical manner so that the materials are bonded to one another while they are extruded. The extrusion is revolved to form a hose whereby each revolution is joined with the previous to form a continuous hose. Spiral bead hoses generally have both a softer un-reinforced cylindrical body for flexibility and a rigid spiral reinforcing bead which maintains the cylindrical shape.
Spiral bead hoses are often extruded from a plastic, such as PVC plastic which is lighter and less costly than reinforced rigid rubber hose. Another benefit of the extruded hose is that it can be made of a clear material to provide a view of water flow, especially when priming the water pump. A further benefit is that the extruded hose presents a smooth inner bore, which allows for unrestricted water flow through the hose. The helical bead helps prevent ballooning of the body of the hose, resists abrasion and helps the hose resist damage when impacted. Spiral bead hoses are well known in the industry and include the Tigerflex® hose by Kuriyama or America Inc., as well as various hoses made by the Kanaflex Corporation, such as their series 100CL.
In use, spiral bead hoses are provided with fittings or couplings at the opposite ends that are configured to supply liquid from a water source to a pump inlet. Most couplings or fittings include a leak free engagement feature to a mating connector, such as male or female threads sealed with a hose gasket. Moreover, most couplings or fittings are formed of a rust-resistant material, such as brass or aluminum.
While the spiral bead hose design provides significant advantages as a suction hose, the spiral design poses problems for securing couplings and fittings to the hose. More particularly, it has been difficult to provide a leak free connection between the hose and the fitting. It has also been difficult to secure the hose from slipping off the fitting under the influence of fluid pressure.
In one approach, the hose is secured to standard hose barb type fittings using U-shaped rods with threaded ends passing through a mounting plate on the outside of the hose. Nuts are tightened down on the threaded ends of the rod to pull the U-shape into tension, thereby compressing the hose against a fitting. The rods are sized to fit within the gaps between the helical bead portions. Even when the U shaped rod wraps more than one turn around the helix of the hose leakage can happen from a spiral void under the bead because the tension rod does not compress the bead. Moreover, the threaded ends of the rods project significantly away from the mounting plate and the hose, making them susceptible to snagging other equipment or workers, or to damage when the fire hose is dragged along the ground.
In another approach a helical banding coil is placed in the gaps between the helical bead portions to provide a smooth surface for banding. The banding does not compress the coil against the bead, so leakage can happen from a spiral void under the bead.
In either of these prior approaches the raised hose barb cannot uniformly impress into sealing engagement in the hose given the spiral nature of the rigid reinforcing bead which must pass across the barb at some point. Retaining spiral bead hose onto standard hose barb fittings using these approaches is difficult because fluid pressure tends to make the rigid bead progressively walk off of the barb.
In another approach, the hose is secured to the fitting with a split two-piece collar with screws spanning the splits. The collar has a spiral form that engages the spiral hose as well as a groove that engages a rib on the tailpiece fitting. The screws are tightened to partially close the splits, thereby compressing the hose against a cylindrical tailpiece extending into the hose, while a rib engages a groove in the collars to retain the collar to the fitting. This approach can solve the retention problem; however, the two-piece collar is of a fixed circumference that is not adapted to compensate for diameter variations of the hose. It has been found that a water-tight seal with this type of collar often requires the use of caulking.
There is a significant need for an apparatus for securing couplings and fittings to a spiral bead hose. It is important that the apparatus provide a leak free seal without compromising the integrity of the hose.